Detectives in London have officially concluded that Italian banker Roberto Calvi was murdered in the city in 1982.

Known as 'God's banker' because of ties to the Vatican, Mr Calvi was found hanging under Blackfriars Bridge but the death was first treated as suicide.

Four people were charged with murder by the Italian authorities last month.

The City of London Police has now completed its own crime report, following a re-investigation, to assist the Italians with their inquiry.

British woman quizzed

London officers are likely to give evidence at the October trial, said a spokesman.

Police said they believe Mr Calvi was probably strangled by two or possibly more people and then hung from scaffolding. When his body was found there were bricks in his pockets, along with thousands of pounds in cash.

CALVI KEY DATES

1971: Becomes chairman of Banco Ambrosiano

1981: Convicted of corruption, but bailed pending appeal

11 June 1982: Leaves Italy with a suitcase of documents

18 June 1982: Body found

July 1982: Suicide verdict

July 1983: Open verdict at second inquest

1998: Calvi's body exhumed

Oct 2002: Forensic report says Calvi murdered

July 2003: Italian prosecutors name four suspects

Sept 2003: City of London Police re-open investigation

Mar 2004: Four appear at pre-trial hearing in Rome

April 2005: Four people charged with murder in Italy

The 62-year-old was president of the struggling Banco Ambrosiano, which later collapsed.

Detectives from the city force had re-opened their investigation into the banker's death in September 2003, following developments with the case in Italy.

Later that year they questioned, then bailed, a 42-year-old British woman on suspicion of conspiring to pervert the course of justice and perjury.

Police said she was freed from her bail earlier this year, after prosecutors decided it would not be in the public interest to pursue the case.

A variety of reasons, including the length of time since the death, were cited, said a police spokesman.

The four people due to stand trial in Italy are Flavio Carboni, his ex-girlfriend Manuela Kleinzig and Pippo Calo and Ernesto Diotallevi.

Mr Calvi's son Carlo hopes the trial will shed light on what happened

Mr Calvi's family have always maintained he did not kill himself.

An initial inquest verdict of suicide was quashed and replaced with an open verdict, and the case has remained unsolved.

Correspondents have said a trial is likely to expose the murky Mafia underworld and financial scandals.

Prosecutors are expected to claim Calvi was killed to prevent him revealing secrets about Italy's political and religious establishment.

He had come to the UK on bail after having been convicted of corruption in Italy.

In 2002 forensic experts appointed by judges in Rome concluded Mr Calvi had been murdered.